Method and apparatus for fabricating flexible tubing

ABSTRACT

Flexible tubing is formed by preforming helix, mounting the helix with its turns oriented in a predetermined manner, applying adhesive to the outer surface of the turns, and winding flexible sheet material around the helix to form an envelope over the helix skeleton. A multiplicity of layers of sheet material can be applied. In fabricating a circular duct, a helix of material of fixed cross-section is supported by a mandrel contacting the turns at spaced points as longitudinal bars spaced 120 degrees. Adhesive is applied by an applicator contacting the outer face of the helix turns with a wiping or rolling contact through rotation of the mandrel or the applicator or both. A broad contact area as afforded by a flattened outer face on each helix turn, sustains sufficient adhesive to penetrate superposed regions of an overlying thin, porous, flexible sheet wound on the helix and adhesively bond another layer of material wound thereover. Insulated tubing can have a plurality of wound layers of insulation in continuous sheet form with the single application of adhesive to bond substrate and at least the first layer of insulation to the helical skeleton and a jacket to retain the outer layers. Tubing is produced on a multistation apparatus. A composite helix spacer rod and expandable mandrel shaft has a pivoted mounting end an opposite end selectively coupled to a first station comprising a helix magazine and a spacer rod drive, to a second station comprising a mandrel drive, and to a third station for jacketing the assembled duct and unloading it from the mandrel shaft. A rack sustaining roof goods and the adhesive applicator for cooperative manipulation relative to the mandrel mounted helix is located at the second station.

Aug. 8, 1972 J. w, HELM|K ETAL 3,682,746

METHOD AND APPARATUS FOR FABRICATING FLEXIBLE TUBING Filed June 6, 19693 Sheets-Sheet 1 E W vM NL R U Hu M5 mww L R n A WLM 5m EWN mww JBJ Hmime d102 8 m oE ATTORNEY Aug. 8, 1972 w HELMlCK ETAL 3,682,746 Y METHODAND APPARATUS FOR FABRICATING FLEXIBLE TUBING Filed June 6, 1969 3Sheets-Sheet 2 FIG. 4

FIG. 6

FIG. 3

FIG. 5

OR JAMES WILLIAM IY L IZK s BROWNE WESLEY GOEBEL BYJOHN MARVIN CURRENTATTORNEY Aug. 8, 1972 J. w HELM|CK ETAL 3,682,746

METHOD AND APPARATUS FOR FABRICATING FLEXIBLE TUBING Filed June 6, 19693 Sheets-Sheet 3 NV TO JAMES WiLLlAM HELM l C k Rs EROWFELL WESLEYGOEBEL Y E ATTORNEY B OHN MARVIN CURRENT FIG. 9

United States Patent 3,682,746 METHOD AND APPARATUS FOR FABRICATINGFLEXIBLE TUBING James William Helmick, Toledo, Brownell Wesley Goebel,Waterville, and John Marvin Current, Jerry City, Ohio, assignors toJohns-Manville Corporation, New York,

' Filed June 6, 1969, Ser. No. 842,766

Int. Cl. 1365!! 81/00 US. Cl. 156-429 16 Claims ABSTRACT OF THEDISCLOSURE Flexible tubing is formed by preforming a helix, mounting thehelix with its turns oriented in a predetermined manner, applyingadhesive to the outer surface of the turns, and winding flexible sheetmaterial around the helix to form an envelope over the helix skeleton. Amultiplicity of layers of sheet material can be applied. In fabricatinga circular duct, a helix of material of fixed crosssection is supportedby a mandrel contacting the turns at spaced points as longitudinal barsspaced 120. Adhesive is applied by an applicator contacting the outerface of the helix turns with a wiping or rolling contact throughrotation of the mandrel or the applicator or both. A broad contact areaas afforded by a flattened outer face on each helix turn, sustainssuflicient adhesive to penetrate superposed regions of an overlyingthin, porous, flexible sheet wound on the helix and adhesively bondanother layer of material wound thereover. Insulated tubing can have aplurality of wound layers of insulation in continuous sheet form withthe single application of adhesive to bond substrate and at least thefirst layer of insulation to the helical skeleton and a jacket to retainthe outer layers.

Tubing is produced on a multistation apparatus. A composite helix spacerrod and expandable mandrel shaft has a pivoted mounting end and anopposite end selectively coupled to a first station comprising a helixmagazine and a spacer rod drive, to a second station comprising amandrel drive, and to a third station for jacketing the assembled ductand unloading it from the mandrel shaft. A rack sustaining roll goodsand the adhesive applicator for cooperative manipulation relative to themandrel mounted helix is located at the second station.

CROSS-REFERENCE TO RELATED APPLICATIONS One form of flexible duct whichcan be produced by the method and apparatus of this invention isdisclosed in United States patent application Ser. No. 831,175 by JamesWilliam Helmick, John Marvin Current and George John Hannes entitledFlexible Conduit, now abandoned which was filed herewith. A preformedhelix of the type for use with this invention and comprising a pluralityof resin bonded filaments, advantageously of glass fibers, can beproduced by the method and with the apparatus disclosed in United Statespatent application Ser. No. 830,- 949 filed herewith by George JohnHannes, James William Helmick, James Arnold Dennis and John MarvinCurrent, entitled Method and Apparatus for Fabricating a Plurality ofFilaments Into a Helix.

BACKGROUND OF THE INVENTION Heretofore flexible tubing has beenfabricated by winding a strand around an expanded mandrel, adhesivelybonding flexible sheet material to the strand, forming end collars forthe tube and applying a jacket to the assembly. Ordinarily, the strandis a metal wire of circular crosssection to which adhesive is applied bydrawing it through a bath prior to winding or by spraying the mandreland wound wire. Such techniques require application of a.

'ice

mold release compound to the mandrel to enable convenient separation ofthe wire helix and overlying sheet material from the mandrel and tominimize the buildup of adhesive on the mandrel. End structures areintegrated in the tubing as preformed collars to which are secured theends of the helix prior to the winding of sheet material thereon or byfabrication on the tubing after the sheet has been wound. The jointbetween the flexible section of tubing and the end collar is a potentialregion of failure, it is expensive to produce, and its results in asubstantial section of tubing which is not flexible. The application ofadhesive by prior techniques has been wasteful and unduly added to theexpense of the tubing, particularly where multiple applications havebeen required. Problems of contact of adhesive with the essentiallycontinuous right circular cylindrical mandrel surface has increased theexpense of the tubing. The formation of the helices on the duct formingmandrel inherently produces helices having circumferential springbackwhich must be constrained by the wall duct and thus imposes limits onthe physical characteristics of the supporting skeleton of the duct.

SUMMARY OF THE INVENTION The present invention is directed to method andapparatus for fabricating flexible tubing having a helical skeleton andmore particularly preformed helical skeleton.

An object of the invention is to improve the production of flexibletubing.

A second object is to reduce the expense of manufacture of flexibletubing.

A third object is to maximize the effective utilization of adhesive inthe manufacture of flexible tubing.

Another object is to simplify the end construction and the fabricationtechniques for such construction for flexible tubing.

A further object is to locate and maintain turns of a preformed helixfor fabrication a flexible tubing.

In accordance with the above objects, one feature of this inventionresides in a method of fabricating a flexible tube by positioning theturns of a preformed helix in an array in a predetermined manner with atleast a portion of the turns regularly spaced. The positioned turns aresupported for rotation and contacted on their outer faces by an adhesiveapplicator. A flexible sheet material is wound over the adhesive coatedfaces to provide an envelope for the helical skeleton. The helix isreleased from its support and removed from the apparatus.

Another feature of the invention comprises mechanism for moving thepreformed helix turns into place. The preformed resin bonded, glassfiber helix of the preferred form has a relatively rigid cross-sectionform so that each turn defines a circle of fixed diameter with a yieldpoint virtually the same as the ultimate strength so that the turns arenot distorted. However, the preformed helix longitudinal dimensions arenot so constrained so it has little torsional strength, is displacedfrom its pitch by its own weight, and has virtually no tendency tomaintain its turns in axial alignment. A preformed helix of thischaracter is collapsed to a bundle of overlying turns and placed upon arotatable shaft of substantially less diameter than the internaldiameter of a helix turn to function as a helix magazine. A rotatablespacer rod of the same general diameter as the magazine shaft and havinga series of collars positioned thereon with separations corresponding tothe helix turn spacings desired is coupled to the magazine shaft and atleast a pair of leading turns of the helix are secured together with thedesired turn spacing. The clamped turns are hung on the rod to straddlea spacer collar and the magazine shaft and spacer rod are then rotatedin the direction of the pitch of the helix. This advances the helixalong the spacer shaft as a screw with adjacent turns spaced by thespacer collars.

A third feature of the invention involves engaging the inner face ofeach positioned turn of the preformed helix with a mandrel of restrictedarea so that the helix is maintained along a straight axis for assemblyof the tubing elements. The mandrel comprises three parallel bars eachmounted on a shaft by at least a pair of parallel pivoted links so thattheir spacing from the shaft can be altered according to the inclinationof the links thereto.

A fourth feature is the means for applying adhesive to the mandrelsupported helix. A horizontal roller having the lower portion of itsperiphery in a pool of adhe- 'sive is brought into engagement with thehelix and the helix and roller are'rotated to transfer adhesive from thepool to the roller to the outer face of the turns of the helix. This isaccomplished Without the application of adhesive to those portions ofthe helix where it serves no useful function or to the mandrel.

Another feature contemplates eliminating the need to apply additionaladhesive where a thin porous sheet is applied to the helix prior to aninsulating blanket by sustaining suflicient adhesive on the outer faceof the helix to penetrate the first layer and bond the blanket thereto.

A further feature involves means affording access to one end of theshaft, assembly and partially processed tube by a plurality of stationsas for the helix positioning means, the mandrel engaging means, and ajacket applicator means. In one embodiment, this is accomplished by aunitary combination of the spacer shaft and the expandable mandrelassembly with a pivoted end support to permit the shaft and assembly tobe shifted between a plurality of arcuately arrayed processing stationsWhile the positioned, preformed helix is maintained thereon.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation, partiallysectioned and broken away in layers, of a portion of a duct producedaccording to this invention;

FIG. 2 is a schematic top view of one layout of the processing stationsof the apparatus of this invention with many elements eliminated toillustrate the relative position of certain elements without obscuringdetail;

FIG. 3 is an elevation of the composite helix mounting means conditionedfor positioning the turns of the preformed helix as it is viewed alongline 33 of FIG. 2 for the first station of the apparatus of thisinvention, many of the elements have been broken away or only partiallyshown in schematic form for clarity;

FIG. 4 is a cross-section of FIG. 3 taken along the line 44;

FIG. 5 is an elevation of the composite helix support of the apparatuswith the helix turns positioned and showing the helix mandrel expandedto its helix supporting condition for further processing;

FIG. 6 is a cross-section of FIG. 5 taken along the line 66;

FIG. 7 is an elevation of the second station of the apparatus with thehelix mount and mandrel drive eliminated as viewed from line 77 of FIG.2;

FIG. 8 is a schematic side view of the second station with details ofthe helix mount and mandrel drive omitted as viewed from the right sideof FIG. 6 and showing the adhesive applicator positioned to engage themounted helix; and

FIG. 9 is an elevation of the third station of the apparatus forapplying jacketing material to the tubing structure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS One form of flexibletubing or duct suitable for utilization in air-conditioning and heatingsystems and produced according to the method and with the apparatus ofthis invention is shown in FIG. 1. -It comprises a skeleton 11 of apreformed helix of phenolic bonded glass fibers COD.

structed as disclosed in the aforenoted patent application entitledMethod and Apparatus for Fabricating a Plurality of Filaments Into aHelix. The skeleton is made up of four rovings each having sixty endswhere each end contains two hundred continuous filaments of glass aboutnine microns in diameter. It is bonded by a phenolic resin into a helixstrand 12 having a cross-section which is semicircular and flat on itsouter surface 13. The strand is about one-eighth inch Wide across face13. A typical duct employs a helix having an inner diameter of each turnof eight inches. In such dimensions, the helix has a well definedcircular cross-section in each turn and is relatively unstable, whenunsupported and standing alone, in the axial dimension so that its axialalignment of successive turns and pitch between successive turns can bealtered with little force.

The duct of FIG. 1 has skeletal end collars 14 made up of a plurality ofturns of the helix bonded together as by orienting them in abuttingside-by-side alignment and applying adhesive thereto. It has a flexibleskeleton section 15 between the collars in which the turns of the helixare spaced at relatively equal intervals.

A thin, flexible, porous sheet material 16, preferably a woven glassfiber scrim, or a bonded glass mat, is adhesively bonded to the flatfaces 13 of each turn of the helix. Thermal insulation which can be aflexible blanket of matted fibers is bonded as a first layer 17 to thelayer 16 and the helix turns by the penetration of the adhesive on faces13 through layer 16 to layer 17. Additional layers 18 of blanket can bewound over layer 17. The skeleton and several layers are jacketed by asuitable material 19 providing a gas impervious wall.

Desired characteristics of low cost, structural strength, thermalinsulation, fire retardance, tolerance to high temperatures, andflexibility are achieved where the adhesive is a vinyl emulsion obtainedas stock No. 6782 HSA, from I. G. Milligan Co. of Milwaukee, Wis., theinsulating blanket of layers 17 and 18 is of glass fibers and the jacket19 is a vinyl chloride tube of about .003 inch wall thickness. However,it is to be understood that alternative materials can be substitutedwhile maintaining the general characteristics desired.

Tubing of the type shown in FIG. 1 is produced by positioning the turnsof a preformed helix 11 as desired in the final product. A mechanicallystable mounting 21 for further processing is provided for the orientedhelix. Adhesive is applied to the outer face 13 of the turns of thehelix by a wiping or rolling contact applicator to confine the adhesiveto that face and avoid fouling the helix mounting mechanism. Theenvelope for the helical skeleton of the tubing is then formed, forexample by rotating the helix and its mount to wrap layers 16, 17 and 18of material thereon. In the example, a thin, porous, flexible layer 16is first applied,

then one or more insulating layers 17 and 18. The first.

layer 16 is secured by the adhesive. Adhesive penetrates the first layerto secure the insulating layer 17 outside it. Where rolled material isemployed, the layers are drawn from rolls mounted for rotation andlocated in proximity to the helix and mount. Multiple layers ofinsulation are formed from a continuous length of sheet material appliedin successive wraps with only the first layer bonded adhesively. Theouter layer or layers are retained on the assembly by a close fittingtubular jacket 19 drawn thereover while layers retain the radialcompression imparted to them by the tension of the winding process.Relief of that tension and the resultant radial expansion of the layersagainst the tubular jacket secures the assembly. It then is removed fromthe helix support to clear the apparatus for another production cycle.

A plan layout of one form of multistation apparatus for producingflexible tubing by the above method is shown in FIG. 2. Three positionsor stations are provided for the helix mounting means 21. These stationsare arcuately arrayed around a bearing 22 mounted to be pivoted in thehorizontal plane. A primary shaft 23 of the helix mount is journaled forrotation around its horizontal axis in bearing 22 so that its distal end24 can be aligned with complementary apparatus at each of the threepositions or stations.

Helix orientation for the tubing is established in the first stationwhile helix mount 21 is aligned therewith. In this station a preformedhelix 11 is maintained in an axially collapsed form in a magazine whichessentially is a stub shaft 25 from which the helix is pendant. A drive26 for the helix turn positioning mechanism is included in this station.

Adhesive is applied to the helix and the wound sheet material is appliedwhile helix mount 21 is inits second position. A drive 27 for rotatingthe helix mount is aligned with and coupled to primary shaft 23 and aframe 28 having end members 29 and 31 for supporting shafts 32 and anadhesive applicator 33 is adjacent the helix and its mount when they arein the second position.

In the third position, helix mount 21 is supported as a cantilever bybearings 22 and has its longitudinal axis aligned with a source 34 ofjacketing material. Suflicient clearance at the distal end 24 isprovided in this station to permit the completed flexible tube to beslid axially along the mount 21 and over the distal end 24 of shaft 23to remove it from the apparatus.

Helix mount 21 is a composite structure best seen in FIGS. 3 through 6showing it in the first position and in the helix turn locating stateand the helix holding state. It comprises a tubular main shaft 23journaled in bearing 22 at one end and having a drive coupling 35 at itsopposite end. A pair of collars 36 (only one of which is shown in FIGS.3, 4 and 6) are fixed at spaced positions along the shaft 23 to providemountings for a helix turn spacer rod 37 and mandrel bars 38. Stanchions39 extend radially from collar 36 to a collar 41 in which the spacer rod37 is journaled for rotation. Lever arms 42 are pivoted at 43 to collar36 and at 44 to mandrel bars 38 to support those bars.

In the first position, mount 21 has spacer rod 37 engaged throughcoupling 45 to shaft 25 of the spacer rod drive 26 and drive coupling 35of the main shaft 23 is free. The collapsed helix 46 is mounted as acoil on shaft 25 prior to the positioning of the mount 21 at its firstposition. Spacing of the helix turns at regular intervals is by spacercollars 47 fixed on spacer rod 37.

To position the helix turns, the leading turn 48 and second turn 49 ofthe preformed helix are drawn from the coil 46 and secured together asby clamp 51 with a separation corresponding to the desired helix pitchover the flexible section 15 of the final product. These coupled turnsare hung over the first spacer collar 47' in the equally spaced seriesof collars 47 each spaced on centers a distance equal to the pitch to beestablished in the helix, three quarters of an inch in the example.Collars 47 are about one-half inch wide and stand about one quarter inchbeyond the spacer rod for a helix made of a oneeighth inch wide strandhaving a semicircular crosssection.

Shaft 25 and spacer rod 37 are rotated in the direction of the pitch ofhelix 11 to advance the helix along spacer rod 37. The frictionalengagement of shaft 25 and rod 37 with the inner face of the helix turnscauses the shaft and rod to roll the helix in the same direction. Thus,when viewed from coupling 45 to the right in FIG. 3, counterclockwiserotation is imparted to the helix coil 46 by rotating shaft 25 and rod37 counter-clockwise. As the helix rotates, it advances as a worm. byintroducing the leading turn into the next gap between spacer collars 47to the right in FIG. 3 from that which it entered on its entered on itspreceding rotation and by carrying succeeding helix turns into thepreviously occupied gaps. The rate of feed varies with the diameter ofthe preformed helix. In general, a range of 1.5 to 15 lineal feet 6 ofpitch per minute can be fed. Control of the feed speed can be by anyconventional electric motor speed control adaptable to the drive motor.

When the helix is distributed across the spacer rod, conventientlysomewhat in excess of six feet in length to produce a tubing section ofsix feet, end collars 14 can be formed by gathering a number of turns inside-by-side abutting relation. This can be done by hand by theoperator. A section 52 at each end of the spacer rod of suificientlength to accommodate the turns of the collar is left free of spacercollars 47 for this purpose. The spacer 52 at the feed end of spacer rod37 is defined by widely spaced spacer collars 47, the first of which 47"facilitates the orderly and gradual introduction of helix turns into theregion of regularly spaced collars 47.

One means of establishing the adjacent relationship of the end collarsis to remove the clamp 51 from the leading turns of the helix and totemporarily secure the abutted turns by a length of pressure sensitivetape (not shown) applied to the inner faces of those turns.

With the skeleton turns oriented, they are next fixed in thatorientation so that they can be further processed without shifting theirrelative positions. Mandrel bars 38 are extended radially from shaft 23to engage the interior of the helix at three locations disposedrespectively 60 to the left 180 and 60 to the right from stanchion 39and thus spacer rod 37. With bars 38 extended against the helix 11, itis raised free of the spacer rod 37 and collars 47 as best seen in FIG.6 and is concentric with shaft 23 so it can be rotated therewith forfurther assembly operations.

Extension of the mandrel bars 38 is by lever collars 53 (only one ofwhich is shown) and their extension levers 54 pivotally connected at 55to collar 53 and at 44 to lever 42 and bar 38. When bars 38 areretracted, collars 53 are adjacent their respective collars 36 andlevers 54 approach parallelism with levers 42, as seen in FIG. 3.Reciprocation of collars 53 to the left as viewed in FIGS. 3 and 5 tospace them from collars 36 move the levers toward a radial position bytheir pivoting action around pivots 44 so that the pivots 44, levers 42and bars 38 move radially outward from shaft 23 as shown in FIG. 5.Collars 53 have open centers across which pins 50 extend throughlongitudinal slots 56 in the walls of shaft 23 to a rod 57 coaxial withthe shaft and reciprocated with respect thereto as by a two-waypneumatic cylinder 58 and piston mounted on the base plate 59 pivotallysupporting bearings 22. Relative rotation between the collars 53 and thecylinder 58 is permitted by a rotary coupling (not shown) which may bebetween the rod 57 and the piston rod from cylinder 58. Air hoses 61 and62 communicate with the ends of the cylinder 58 on each side of theactuating piston so that control valve 60 can be set by the operator toextend or retract the mandrel bars 38.

With the mandrel bars extended to engage the interior of each turn ofhelix 11 at points spaced the spacer rod 37 is uncoupled from feed rod25 and drive 26 by release of coupling 45. This is done by axial motionof one of the interfitting coupling elements in a manner which is wellknown. The helix mount 21 is then pivoted around the pivot for baseplate 59 to the second position of FIG. 2 and mandrel shaft 23 isengaged with mandrel drive 27 by coupling 63. The duct skeleton isconditioned to receive adhesive and the layers 16, 17 and 18.

A frame 28 having ends 29 and 31 supports the elements employed infurther fabrication of the flexible duct as can be seen in FIGS. 2, 7and 8. Adhesive applicator 33 comprises a trough 64 on the ends of whichare journals 65 in which is rotatably supported a coating cylinder 66.As cylinder 66 is rotated, its lower portion of the cylinder dips into apool 67 of adhesive, FIG. 8, to pickup adhesive from the pool. Cylinder66 is moved to and from helix skeleton 11 by a pneumatic drive 68comprising cylinders pivoted at 70 to frame 28 having piston rodsextending to pivotal connections 69 to support arms 71 for theapplicator assembly. Applicator support arms 71 are pivoted to frame 28to enable the applicator to be raised in an are so that a portion ofcylinder 66 protruding from trough 64 engages the outer face of thehelix skeleton 11 while its rotational axis is parallel to the axis ofrotation of the skeleton.

Adhesive is applied by rotating skeleton 11 while cylinder 66 rotates topick up adhesive from the pool and deposit it on the outer face of thehelix turns. All of the circumference of the helix is coated. Rotationof the mandrel by drive 27 is through the drive shaft 72 and coupling 63to shaft 23 and is controlled by the operator as by a foot pedalrheostat switch 73 where the speed of the drive is a function of thedegree to which the switch is depressed. Conveniently, the cylinder 66can be driven (by means not shown) as by an electric motor mounted onone. of arms 71 coupled to the shaft of cylinder 66 through a drive beltand an overriding clutch which permits the cylinder to be driven by thefrictional engagement of helix 11 when that helix is driven at a fasterspeed than the cylinder.

When the helix is coated over its entire outer circumference, theadhesive applicator is retracted by actuating the two-way drive 68 fromits two-way control 74 mounted on frame 28. Control 74 can be a leveractuated pneumatic valve and can be arranged to energize the drive motorfor rotating cylinder 66 coincidental to the advance of the applicatorfrom its retracted position (by means not shown).

Sheet material is next applied to the adhesive coated skeleton 11. Whereduct, as shown in FIG. 1, is to be produced, a first layer 16 of thin,porous, flexible sheet such as woven glass scrim is drawn from payoffroll 75 over tensioning guide rolls 76 and 77 and wrapped around theadhesive coated skeleton 11. The operator draws the material of layer 16which is pendant from guide roll 77 down, underneath and up aroundskeleton 11 to initiate the wrap and then actuates the mandrel drive bymeans of foot pedal 73 as needed to complete the wrap. When a completelayer has been applied, the layer is separated from the goods frompayoif roll 75 by cutting the goods with a blade (not shown) fitted incutting guide 78.

Cutting guide 78 can be a roller having a longitudinal slot 79 and canbe mounted to extend the roll goods from frame 28 toward the mandrelmounted skeleton. A mounting arm 81 supports guide roller 78 from pivots82 to frame 28 so that pneumatic extension drive 83 can be controlled bypneumatic control valve 84 to either a retracted or extended position.Drive 83 may be a two-way drive cylinder pivoted to frame 28 at pivot 85and having its piston rod pivoted to cutting guide arm 81 at pivot 86.The cutting guide can be extended after the Wrap of the roll goods hasbeen started on skeleton 11, thereby aiding in maintaining the goodsfirmly against the skeleton. It is retracted upon completion of theseverance of the wrapped goods from its supply roll.

Layers 17 and 18 are next wrapped over layer 16, by drawing the rollgoods, in the example flexible fiber glass blanket from payoff roll 87over tensioning guide rolls 88 and 89, beneath scrim covered helix 11and up around the helix. The cutting guide 78 can then be advanced andthe foot pedal operated to rotate the mandrel drive 27, as needed. Whenthe desired number of wraps have been applied, the roll goods are cutoif using the cutting guide 78 as described. The final wrap is held inplace temporarily while the mandrel assembly, and the partiallycompleted duct are moved to position 3 in FIG. 2 for jacketing; When thedesired types of covering material, which may include, in addition tothe fiber glass blanket and scrim of the example, alternative insulatingmaterials, aluminum foil or any other flexible type roll goods, arewrapped, those goods which are compressible are slightly compressedradially by the tension of the Wrapping operation. The compression isretained until the subassembly is jacketed by placing an elongatedweight as a metal rod 91 on the upper surface of the duct parallel toits longitudinal axis. This can be done prior to the cutoff of the rollgoods from its payoff roll.

Coupling 63 is released from shaft 23 and the mandrel, subassembly andholddown rod 91 are swung around the pivot for base plate 59 to axialalignment with the jacketing material 19, as shown in FIG. 9. Onesuitable jacket is a rolled tube of vinyl chloride sheet materialsupported on rack 92 having roll supports 93 for a shaft 94 on which aroll 95 of jacketing is mounted. A table 96 integral with the rack 92maintains a free end of the tubing conveniently available to the end ofthe duct subassembly in position 3. Tubing 19 is drawn over the free endof the subassembly and along its length to cover the insulation 18. Itis then severed from the roll beyond the free end of the insulation andthe holddown rod 91 is withdrawn from within the jacket therebypermitting the radially compressed insulation to expand and bind thejacket to the structure.

The completed duct is removed from the mandrel by transferring themandrel extension control 60 to its retraction position whereby theextension drive 58 moves rod 57 to the right as viewed in the severaldrawings. Collars 53 are thereby moved to the right and then extensionlevers 54 are moved toward parallelism with levers 42 to retract themandrel bars 38 toward shaft 23 and release the helix 11 therefrom. Theduct section is then slid axially off of the free end of the helix mount21 to clear the apparatus for another processing cycle.

Another cycle is initiated by mounting a coil of the resin bondedpreformed helix on the shaft 25, rotating the helix mount 21 to locatethe spaced rod 37 in the uppermost position and coupling that red to theshaft 25 by coupling 45.

It is to be appreciated that various modifications can be incorporatedin the apparatus to facilitate manipulation of its parts and thematerial it utilizes. The apparatus lends itself to production of arange of sizes of duct by virtue of the range of expansion of themandrel bars 38 and can accommodate different helix mounting assemblies21 where duct beyond the range of the illustrated mounting is to beproduced. While a particular form of helix coil positioning mechanismhas been disclosed, that mechanism can be modified as by a serpentinesupport across which the leading turn of the helix is carried whilerelative motion between the support and helix causes the following helixturns to fall into spaced valleys in the support. Other variants caninclude a turret array of work stations whereby the helix mount 21 ismaintained in one position and the several complementary combinations ofapparatus movedvinto position relative to the mount as by positioningthehelix feed and spacer rod drive into alignment with shaft 23 followedby the mandrel drive 27 and then the jacketing apparatus and supply.

In View of the modifications and variations available, it should beunderstood that the above disclosure is presented as illustrative and isnot to be read in a limiting sense.

We claim:

1. Apparatus for positioning a plurality of turns of a preformed helixcomprising a rod of circular cross-section, a plurality of enlargementson said rod spaced on centers corresponding to the pitch desired forsaid helix, said enlargements each having a longitudinal extent alongsaid rod less than the spacing between adjacent turns of said helix todefine reduced regions on said rod of greater length longitudinallythereof than the width of the strand of which said helix is formed;means for rotating said rod in the direction of advance of said helixwhile said helix is pendant thereon; and means within said helix toengage said helix internally to maintain adjacent turns of said helixspaced the pitch desired for said helix independently of said rod over alength of said helix.

2. Apparatus according to claim 1 wherein means is secured to at leasttwo leading turns of said helix to space those turns the pitch desiredfor said helix while said helix is in contact with said rod.

3. Apparatus according to claim 1 including end sections of said rodhaving a reduced region of an extent to accommodate a plurality of turnsof said helix in sideby-side abutting relation.

4. Apparatus for positioning a plurality of turns of a preformed helixcomprising a rod of circular cross-section, a plurality of enlargementson said rod spaced on centers corresponding to the pitch desired forsaid helix, said enlargements each having a longitudinal extent alongsaid rod less than the spacing between adjacent turns of said helix todefine reduced regions on said rod of greater length longitudinallythereof than the width of the strand of which said helix is formed;means for rotating said rod in the direction of advance of said helixwhile said helix is pendant thereon; an expandable mandrel secured tosaid rod; and transfer means to transfer said mandrel between acondition free of the turns of said helix pendant from said rod andengaging the turns of said helix to raise said helix free of said rod.

5. Apparatus according to claim 4 wherein supports are journaled on saidrod and spaced longitudinally thereof; said expandable mandrel comprisesa shaft journaled on said supports parallel to said rod, a plurality ofmandrel bars parallel to said shaft and distributed around said shaft toproduce a pattern of support points for said helix and means extensiblysupporting said mandrel bars on said shaft; and said transfer meansextends and retracts said bars relative to said shaft.

6. Apparatus according to claim 5 including a releaseable couplingbetween said rod and said means for rotat ing said rod; and means forrotating said shaft.

7. Apparatus according to claim 6 including an adhesive applicatoradapted to contact said helix while it is engaged and held by saidmandrel bars; and means to advance and retract said applicator fromcontact with said helix.

8. Apparatus according to claim 7 wherein said adhesive applicatorcomprises a trough for containing a liquid adhesive; a transfer rolljournaled for rotation on said trough with a portion of said rollprotruding from said trough and another portion of said roll in theliquid adhesive; a pivotal mounting for said trough; and means to pivotsaid roll into and out of contact with said helix.

9. Apparatus according to claim 6 including a source of flexible sheetmaterial for covering said helix; means to secure the sheet material tosaid helix; and control means for controlling the rotation of said shaftby said rotating means while the sheet material is wrapped on saidhelix.

10. A mandrel for supporting a helix comprising a shaft; at least threemandrel bars parallel to said shaft and distributed around said shaft ina helix support pattern; means to extend and retract said mandrel barsfrom said shaft to engage the interior of said helix; said shaft havinga hollow region, including at least two links pivotally connectedbetween said shaft and each of said mandrel bars; a rod reciprocativewith respect to said longitudinal dimension of said shaft and fittingwith the hollow region thereof; at least two extension links pivotallyconnected between said rod and each of said mandrel bars;

10 and a drive to reciprocate said rod with respect to said shaft andthereby extend and retract said mandrel bars.

11. Apparatus according to claim 10 wherein said mandrel bars engageeach turn of the supported helix at essentially point areas of contactto support the helix in a horizontal position remote from said shaft,and wherein said mandrel bars are three in number disposed around saidshaft at intervals of angular degrees.

12. Apparatus according to claim 10 including means to rotate said shaftaround its longitudinal axis whereby said mandrel bars and helix engagedthereby are rotated.

13. Apparatus according to claim 12 including an adhesive applicatorengageable with the outer face of each turn of said helix when saidhelix is engaged by said mandrel bars whereby said adhesive is appliedto said outer face of each turn.

14. Apparatus according to claim 13 wherein said adhesive applicatorincludes a roller for carrying adhesive and transferring adhesive toeach turn of said helix by a rolling contact; and including means toadvance said roller into contact with said helix and retract said rollerfrom said helix.

15. The method of positioning and maintaining the turns of a helix atregular intervals longitudinally thereof which comprises hanging saidhelix with its longitudinal axis generally horizontal; aligning a rodmember having a series of regularly spaced prot-uberances thereon withsaid helix; securing to a plurality of leading turns of said helix ameans to maintain adjacent leading turns of the helix spaced the pitchdesired; introducing a secured leading turn of said helix between afirst pair of said protuberances; rotating said helix in the directionof the pitch thereof whereby said helix advances along said rod memberas a screw; and engaging the helix internally with a mandrel means tomaintain adjacent turns of said helix spaced the pitch desired for saidhelix independently of said rod member over a length of said helix.

16. The method of positioning and maintaining the turns of a helix atregular intervals longitudinally thereof which comprises hanging saidhelix with its longitudinal axis generally horizontal; aligning a rodmember having a series of regularly spaced protuberances thereon withsaid helix; introducing a first turn of said helix between a first pairof said protuberances; rotating said helix in the direction of the pitchthereof whereby said helix advances along said rod member as a screw;aligning means within said helix to maintain adjacent turns of the helixspaced the pitch desired for said helix; and engaging the helixinternally with said maintaining means to secure the turns of said helixindependently of said rod member subsequent to the step of advancingsaid helix along said rod member.

References Cited UNITED STATES PATENTS 2,995,312 8/1961 Nagel 242-54 R3,107,455 10/ 1963 Gloor 226200 X 3,439,851 4/1969 Rum 2%6-200 X3,500,877 3/1970 Lingen 226168 UX RICHARD A. SCI-IACHER, PrimaryExaminer U.S. Cl. X.R.

